1. Field of the Invention
The present application relates to an over-current protection device and a battery protection circuit assembly containing the same.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Because the resistance of conductive composite materials having a positive temperature coefficient (PTC) characteristic is very sensitive to temperature variation, it can be used as the material for current sensing devices, and has been widely applied to over-current protection devices or circuit devices. The resistance of the PTC conductive composite material remains extremely low at normal temperature, so that the circuit or cell can operate normally. However, when an over-current or an over-temperature event occurs in the circuit or cell, the resistance instantaneously increases to a high resistance state (e.g. at least 102Ω), so as to suppress over-current and protect the cell or the circuit device.
For battery protection, a known method is to surface-mount an over-current protection device on a circuit board, so as to form a protection circuit module (PCM), which is coupled to positive and negative electrodes of a battery through, for example, strap interconnects to form a protection circuit.
To improve manufacturing efficiency, the over-current protection device is in an attempt to be in connection with the strap interconnects through spot-welding or reflow. However, for spot-welding, the temperature would be somewhere near or above 1500° C., and thus electrical properties of the over-current protection device would be damaged due to high temperature. To prevent damage to the over-current protection device, the impact of high temperature needs to be overcome effectively.